1. Missed the live Ask the Expert event?
    Catch up on the conversation with Ken Hutcheson, President of U.S. Lawns in the Franchising forum plus sign up to receive a FREE eBook on how to grow your landscape business.

    Dismiss Notice

briggs 8hp issues

Discussion in 'Mechanic and Repair' started by Metalmacguyver, May 16, 2006.

  1. Metalmacguyver

    Metalmacguyver LawnSite Member
    Messages: 45

    i have a B/S 8hp horiszontal shaft engine mounted on a DR brush/field mower.

    mod:195422 type:1136 01 code:9311031A

    i recently came into this machine and as the previous owner said, it had issues.

    i found one problem and fixed it. that was the hole in the carb float that had let gas into it, reducing its flotation and thus letting the gas flood the whole carb. i repaired the float.

    however it is still having issues. it is not running right because the needles had been adjusted to try to deal with the super rich situation. i have been working on re tuning it with some success. it is now running but not very well. it is running rough with alot of govoner action. basically the engine speed is varying between what i would guess to be 2800 and 3600 on 1 second intervals.

    i also decided to see what the head looked like. so i pulled the head and while inspecting the cylinder i noticed what looked like some carbonization from some slight blow by. it only goes to about a half of an inch below the top of the piston a TDC.

    i have two questions.
    what are the factory needle settings?
    what other problems might i be missing?

    Thanks in advance for all of your help.
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    The top adjuster is for the low speed and should be opened 1 1/2 turns, The bottom adjuster is for the high speed it should be opened 2 turns. Now this is just a starting point to get the engine running, Once warmed for about 5 minutes move the throttle to idle and slowly adjust the low speed inward until the idle starts dropping then back it back out until it starts to drop then adjust back in to the middle of the two idle drop points. Then throttle up to speed and adjust the high speed the same as above. If it still hunts after adjusting you may need to clean the inside of the carb. checking the main jet. Also make sure the small spring that slides over the carb. linkage rod is there and hooked up.Oh you can get to the main jet by removing the high speed adjuster from the bottom of the carb. then insert a small screw driver up into the hole and back it out without removing the hole carb, This must be removed before you can remove the top of the carb. for cleaning should you need to.
    Good Luck
  3. Metalmacguyver

    Metalmacguyver LawnSite Member
    Messages: 45

    um can you post a picture or diagram of the carb so you can show me where the spring that goes over the linkage is? i just went and looked at it and it is not there. its a really simple set up and there is only one place that it could go and its not there. the only spring thats there is the gov. spring thats connected to the throttle. thanks for the tip on taking the car apart. once i saw how it was set up i was like how the heck do i take this thing apart. if i couldnt figure it out i would have taken it to my uncle who is a retired small engine mechanic that used to have his own shop. thanks again!
  4. oldrustycars

    oldrustycars LawnSite Senior Member
    Messages: 301

    i think the spring rob speaks of goes over the rod that goes from the governer arm to the carb, then hooks to the carb and the governer arm. keeps the rpm from surging.
  5. Metalmacguyver

    Metalmacguyver LawnSite Member
    Messages: 45

    yeah that is definately missing and it is surging. do you know if i can get this spring alone or do i need a carb kit or something of that sort?
  6. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    The only way to get the spring is separately and the part # is 690545 and the cost is $ 4.03. The rod goes thru the center of the spring as oldrusty said and hooks in the small hole on the gov. arm and if there isn't a small hole on the throttle shaft put it in the same hole the rod goes thru. The break-down doesn't show the spring in place but to the side of all the linkages.
  7. Metalmacguyver

    Metalmacguyver LawnSite Member
    Messages: 45

    what does the spring actually do? remove any slop from the linkages?
  8. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Thats exactly what it does, The spring needs to be in place to eliminate that as being the problem because it's a cheep easy fix.
  9. Jason Rose

    Jason Rose LawnSite Fanatic
    Messages: 5,858

    HEY! I learned something tonight! I have messed with small engines for years, with no "formal" training outside of small engines class in highschool and I have never known what the purpose to the springs wrapped around the linkages was!
  10. Metalmacguyver

    Metalmacguyver LawnSite Member
    Messages: 45

    i have never had any training either. not even a class in school. i have just been using my intuition, common sense and my trusty ratchet set to figure out how these small engines work and to fix them once i know how they work. it does help that my uncle is a retired small engine repair mechanic. just last night he helped me out with a bent crank on a toro mower. the crank aint bent any more! and he gave me the straightener to boot!

Share This Page